Synthesis, structures and electrochemical properties of amino-derivatives of diiron azadithiolates as active site models of Fe-only hydrogenase

The preparation and characterization of two novel amino-incorporated sulfur-bridged dinuclear iron (I) complexes of the type [NR(μ-SCH2)2]Fe2(CO)6, one being amino protected [N(CH2CH2NHTs)(μ-SCH2)2]Fe2(CO)6 (8) and the other [(μ- SCH2)2Fe2(CO)6NCH2CH2N (μ-SCH2)2]Fe2(CO)6 (9) are described. These two complexes are readily prepared in a SN2 manner between double lithium anion and bis(chloromethyl) amine derivatives. The structures of 8 and 9 were characterized by IR, 1H, 13C NMR, MS and HRMS spectra and further determined by X-ray analyses. Protonation of complex 8 gave the mono N-protonated product, while for 9 the protonation occurred in both of the N atoms. The redox properties were evaluated by cyclic voltammograms. It was shown that these two complexes can catalyze electrochemical reduction of proton to molecular hydrogen.